This paper introduces a revised model for the development of basic computation skills. The model draws on four key phases, which have proven to be important for the development of calculation strategies and stresses the use of gestures and the verbalisation of concrete and mental images. This seems to be of crucial importance for children with special needs as the case of Mia illustrates. Context is a university based intervention program that seeks to support children who struggle with the learning of basic arithmetic concepts and skills.